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So excited to share the latest work from my thesis - how do we go about rationally designing antimicrobial targeted prodrugs and does it even matter? (hint- it should)
A huge thanks to all the folks who have collaborated on this and made it possible.
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/1 https://twitter.com/biorxivpreprint/status/1339008721847017472
A huge thanks to all the folks who have collaborated on this and made it possible.
A
-/1 https://twitter.com/biorxivpreprint/status/1339008721847017472
We know antimicrobial resistance is going to be a huge. Surprisingly few antimicrobials target metabolic processes because the inhibitors you'd need to make are hard to get into cells (= no 
). If we could get them in, we could hugely expand the druggable space.
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). If we could get them in, we could hugely expand the druggable space./2
Lipophilic ester prodrugging is a common med chem technique and seemingly gives free cellular entry to a lot of polar anti-metabolite drugs (yay!).
Why don't we just do that then? Unfortunately human esterases like to chew apart these prodrugs, erasing all the above benefits.
Why don't we just do that then? Unfortunately human esterases like to chew apart these prodrugs, erasing all the above benefits.
I know what you're saying now, Justin- I learned that esterases are super promiscuous, there's no way you'll be able to target prodrug activation to a specific esterase by just switching the prodrug substrate around.
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In one of the *coolest* experiments in my graduate career (the result of a lunch with @eamueller_) we show that the identity of an ester promoiety dramatically affects the rate of prodrug activation in whole cells (we have movies!).
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Ok, so promoieties matter. Can we design one that is selectively activated by microbes?
First we have to know which bacterial esterase we're aiming for. Using 2(F+R)genetic screens, we find that 2 esterases are responsible for activation of carboxyester prodrugs in S. aureus
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First we have to know which bacterial esterase we're aiming for. Using 2(F+R)genetic screens, we find that 2 esterases are responsible for activation of carboxyester prodrugs in S. aureus
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(GloB and FrmB). While the native cellular role of these enzymes is slightly hazy (probably cellular detoxification?) we show that they moonlight as prodrug activators!
Note- we've previously described GloB's role in prodrug activation here- https://twitter.com/odomjohnlab/status/1322138900287148032?s=20
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Note- we've previously described GloB's role in prodrug activation here- https://twitter.com/odomjohnlab/status/1322138900287148032?s=20
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Next, we wanted to see what types of promoieties GloB and FrmB may be able to cleave. Using a 32-compound substrate library, we make a decent start at establishing the specificity of these esterases.
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However, the world of chemistry is huge and 32 compounds isn't going to cut it. It would be great to have a crystal structure so we can rationally design new substrates. With help from the Jez lab (@ WUSTL) we solved the structures of BOTH FrmB and GloB!
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With structure-guided design now possible, we wanted to turn back to the question "does any of this actually matter for humans?". Using the same 32-compound substrate library, we sin against the 10 enzyme commandments set forth by Arthur Kornberg, and screen whole human and
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mouse sera to determine ester substrate preferences. We find that 1) mouse sera =/= human sera, begging the question, are mice really an appropriate model for human prodrug studies? and 2) there are differences between whole sera preferences and GloB and FrmB preferences!
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In short, targeting prodrugs to S. aureus (and probably microbes in general) *should be possible*. TONS of follow-up questions on the underlying biology of these two enzymes, prodrug transit in microbes, the genus/species differences in activation. Also, making the compounds!
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So excited to see what comes next from this amazing team, and so happy to have had help from the amazing labs of @pauljplanet, Dowd Lab, @Muller_Lab, Jez Lab, @PetraLevin and of course my mentor @odomjohnlab!
/fin
/fin
